Apparatus, system, and method for handling aligned wafer pairs

ABSTRACT

An industrial-scale apparatus, system, and method for handling precisely aligned and centered semiconductor wafer pairs for wafer-to-wafer aligning and bonding applications includes an end effector having a frame member and a floating carrier connected to the frame member with a gap formed therebetween, wherein the floating carrier has a semi-circular interior perimeter. The centered semiconductor wafer pairs are positionable within a processing system using the end effector under robotic control. The centered semiconductor wafer pairs are bonded together without the presence of the end effector in the bonding device.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Application Ser. No.62/161,988 filed May 15, 2015, entitled, “Apparatus and Method forHandling Aligned Wafer Pairs,” the entire disclosure of which isincorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to an apparatus and a method for handlingaligned wafer pairs and in particular to an end effector configured tocarry aligned semiconductor wafer pairs with a precision suitable forwafer-to-wafer bonding applications.

BACKGROUND OF THE DISCLOSURE

Wafer-to-wafer (W2 W) bonding is deployed in a wide range ofsemiconductor process applications for forming semiconductor devices.Examples of semiconductor process applications where wafer-to-waferbonding is applied include substrate engineering and fabrication ofintegrated circuits, packaging and encapsulation ofmicro-electro-mechanical-systems (MEMS) and stacking of many processedlayers (3D-integration) of pure microelectronics. W2 W bonding involvesaligning the surfaces of two or more wafers, transporting the alignedwafers into a wafer bonding chamber, bringing the wafer surfaces incontact and forming a strong bond interface between them. The overallprocess yield and manufacturing cost of the so produced semiconductordevices and ultimately the cost of the electronic products thatincorporate these devices depend greatly upon the quality of thewafer-to-wafer bond. The quality of the W2 W bond depends upon theaccuracy of the wafer alignment, the preservation of the wafer alignmentduring the transport and the bonding process, and the uniformity andintegrity of the bond strength across the wafer bond interfaces.Furthermore, extreme care is needed during the transport, positioning,centering and alignment of the wafers in order to avoid fracture,surface damage, or warping of the wafers.

FIG. 1A depicts a schematic diagram of a conventional transport fixtureused to transport aligned wafers from an aligner to a bonder, inaccordance with the prior art. Traditionally, a wafer pair 18 is alignedin an aligner station 50 and the aligned wafer pair 18 is secured onto atransport fixture 24, as shown in FIG. 1A. The transport fixture 24carries the aligned wafer pair 18 to the bonding station 60 and to anyfurther processing stations. A prior art transport fixture 24 isdescribed in U.S. Pat. No. 7,948,034 issued on May 24, 2011 and entitled“APPARATUS AND METHOD FOR SEMICONDUCTOR BONDING”, the contents of whichare expressly incorporated herein by reference.

FIG. 2A depicts the conventional transport fixture of FIG. 1A and asdiscussed relative to FIG. 3, in accordance with the prior art, and FIG.2B depicts an enlarged view of the clamping assemblies of theconventional transport fixture of FIG. 2A, in accordance with the priorart. FIG. 3 is a schematic depiction of loading an aligned wafer pairinto a bonding chamber using a conventional transport fixture, inaccordance with the prior art. Referring first to FIG. 3, a conventionaltransport fixture 24 is sized to hold an aligned wafer pair (not shown)and a transport device 16 is used to move the transport fixture 24 andthe aligned wafer pair into and out of the bonding chamber 12. In oneexample, transport device 16 is a transport arm or slide that isautomated or otherwise manually operated.

As shown in FIG. 2A, transport fixture 24 is a circular shaped ring 280,often constructed from titanium, and includes three noses 280 a, 280 b,280 c that are symmetrically spaced about the circular shaped ring 280that act as support points for a base wafer. Proximate to each of thethree noses 280 a, 280 b, 280 c are three spacer and clamp assemblies282 a, 282 b, 282 c arranged symmetrically at the periphery of thecircular ring at 120 degrees apart. Each spacer and clamp assembly 282a, 282 b, 282 c includes a spacer 284 and a clamp 286. Spacer 284 isconfigured to set two wafers at a predetermined distance. Spacers withdifferent thicknesses may be selected for setting different spacingsbetween the two wafers. Once the spacers are inserted between thewafers, the clamp 286 is clamped down to lock the position of the twowafers. The clamp 286 may be a single structure or a linkage that movesdownward to contact an upper wafer to retain it in position on thetransport fixture 24. Each spacer 284 and each clamp 286 areindependently activated by linear actuators 283 and 285, respectively.

For the bonding process, two aligned wafers are placed in the carrierfixture 24 and are spaced apart with spacers 284 and then clamped downwith clamps 286. The fixture with the clamped wafers is inserted in thebonding chamber 12 and then each clamp 286 is unclamped one at a time,and the spacers 284 are removed. Once all spacers 284 are removed andthe two wafers are staked together with a pneumatically controlledcenter pin. Then, a force column is applied to facilitate the bondingprocess in the bonding device 12 throughout the high-temperature bondingprocess.

Within the industry, it is known that the transport fixtures 24 can beheavy and challenging for the transport device 16 or a robot to handle.Further, once they are positioned within the bonding device 12, thetransport fixtures 24 remain in the bonding device 12 throughout theduration of the bonding process, thus subjecting the transport fixtures24 to bonding environments of up to 550° C. temperatures, as well aschamber gasses and/or pressures that may be used within the bondingdevice 12. In particular, the transport fixture 24 may be positioned foran hour or more in a location only a few millimeters away from an outercircumference of a heated chuck of the bonding device 12, such that thetransport fixture 24 gets very hot. These conditions place a significantamount of stress on the transport fixtures 24, and especially on theintricate mechanics of the spacers 284 and clamps 286. As a result, overtime, the transport fixtures 24 become unreliable and requiresignificant servicing including sensitive adjustment of the mechanics,which has high costs and takes substantial time.

In other implementations, the aligned wafer pair is bonded temporarilyand the temporarily bonded wafer pair is transported into the bondingstation and any other processing stations. Temporary bonding of thewafers may be used to minimize alignment shift error during processing.The temporary wafer bonding techniques include bonding the centers orthe edges of the wafers with a laser beam, bonding the centers or theedges of the wafers with a temporary tack adhesive and bonding thecenters or the edges of the wafers via hybrid fusion. The bonded waferpair is then transported to the bonding device with a transport fixtureor similar, conventional transportation devices. The laser bondingtechniques require at least one laser-transparent wafer and the adhesivebonding techniques may contribute to contamination of the wafersurfaces.

Accordingly, in light of the aforementioned deficiencies andinadequacies, it is desirable to provide an industrial-scale device forhandling precisely aligned and centered semiconductor wafer pairs forwafer-to-wafer bonding applications with high throughput and the abilityto handle all types of wafers without introducing any contaminants.

SUMMARY OF THE DISCLOSURE

Embodiments of the present disclosure provide a system and method for anend effector end effector apparatus for handling wafers. Brieflydescribed, in architecture, one embodiment of the system, among others,can be implemented as follows. The end effector apparatus has a framemember and a floating carrier connected to the frame member with a gapformed therebetween, wherein the floating carrier has a semi-circularinterior perimeter. A plurality of vacuum pads are connected to thefloating carrier, wherein each of the plurality of vacuum pads extendsinward of the semi-circular interior perimeter of the floating carrier.

The present disclosure can also be viewed as providing a system forplacing aligned wafer pairs into a processing device. Briefly described,in architecture, one embodiment of the system, among others, can beimplemented as follows. An end effector has a frame member and afloating carrier for carrying wafers in spaced alignment, wherein thefloating carrier is movably connected to the frame member. A robotic armis connected to the end effector. A processing device has a processingchamber, wherein the frame member and floating carrier are positionedwithin the processing chamber, and wherein the floating carrier isdecoupled from the frame member.

The present disclosure can also be viewed as providing a system forplacing aligned wafer pairs into a processing device. Briefly described,in architecture, one embodiment of the system, among others, can beimplemented as follows. An end effector has a frame member and afloating carrier, wherein the floating carrier is movably connected tothe frame member, and wherein a plurality of clamp-spacer assemblies areconnected to at least one of the frame member and the floating carrierto carry wafers in spaced alignment. A robotic arm is connected to theend effector. A bonding device has a bonding chamber, wherein the framemember and floating carrier are positioned within the bonding chamberbefore a bonding process and removed from the bonding chamber during thebonding process.

The present disclosure can also be viewed as providing methods ofplacing aligned wafers into a bonding device. In this regard, oneembodiment of such a method, among others, can be broadly summarized bythe following steps: securing wafers in spaced alignment with an endeffector having a frame member and a floating carrier movably connectedto the frame member; using a robot to move the end effector, therebymoving the wafers into a bonding chamber of a bonder; unloading thewafers from the end effector; removing the end effector from the bondingchamber; and bonding the wafers.

Other systems, methods, features, and advantages of the presentdisclosure will be or become apparent to one with skill in the art uponexamination of the following drawings and detailed description. It isintended that all such additional systems, methods, features, andadvantages be included within this description, be within the scope ofthe present disclosure, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1A depicts a schematic diagram of a conventional transport fixtureused to transport aligned wafers from an aligner to a bonder, inaccordance with the prior art;

FIG. 1B depicts a schematic diagram of a transport device and methodused to transport aligned wafers from an aligner to a bonding device, inaccordance with a first exemplary embodiment of this disclosure;

FIG. 2A depicts the conventional transport fixture of FIG. 1A and asshown in FIG. 3, in accordance with the prior art;

FIG. 2B depicts an enlarged view of the clamping assemblies of theconventional transport fixture of FIG. 2A, in accordance with the priorart;

FIG. 3 is a schematic depiction of loading an aligned wafer pair into abonding chamber using a conventional transport fixture, in accordancewith the prior art;

FIG. 4 depicts an end effector used to transport aligned wafers into andout of processing chambers, in accordance with the first exemplaryembodiment of this disclosure;

FIG. 5 depicts a top view of the end effector of FIG. 4 holding a pairof aligned wafers, in accordance with the first exemplary embodiment ofthis disclosure;

FIG. 6 depicts a bottom view of the end effector of FIG. 4 holding apair of aligned wafers, in accordance with the first exemplaryembodiment of this disclosure;

FIG. 7 depicts a partially transparent bottom view of the end effectorof FIG. 4 holding a pair of aligned wafers, in accordance with the firstexemplary embodiment of this disclosure;

FIG. 8A depicts a cross-sectional view of a portion of the end effectorof FIG. 4 holding a pair of aligned wafers, in accordance with the firstexemplary embodiment of this disclosure;

FIG. 8B depicts a cross-sectional view of the end effector of FIG. 4holding a pair of aligned wafers, in accordance with the first exemplaryembodiment of this disclosure;

FIG. 8C depicts a cross-sectional view of the end effector of FIG. 4holding a pair of aligned wafers, in accordance with the first exemplaryembodiment of this disclosure;

FIG. 8D depicts a cross-sectional view of the end effector of FIG. 4positioned on a storage station, in accordance with the first exemplaryembodiment of this disclosure;

FIG. 9 depicts a bottom view of the end effector with adjustable vacuumpads for holding wafers of different sizes, in accordance with the firstexemplary embodiment of this disclosure;

FIGS. 10A-10B depict the end effector in use with a robotic arm, inaccordance with the first exemplary embodiment of this disclosure;

FIG. 11A-FIG. 11H schematically depict the steps of unloading an alignedwafer pair from an aligner with the end effector of FIG. 4, inaccordance with the first exemplary embodiment of this disclosure;

FIG. 12 is a schematic diagram of a wafer aligner, in accordance withthe first exemplary embodiment of this disclosure;

FIGS. 13A-13I schematically depict the steps of loading an aligned waferpair into a bonder with the end effector of FIG. 4, in accordance withthe first exemplary embodiment of this disclosure;

FIG. 14 depicts loading an aligned wafer pair into a bonder with the endeffector of FIG. 4, in accordance with the first exemplary embodiment ofthis disclosure;

FIG. 15A depicts a schematic view of pinning two wafers via a singlecenter pin, in accordance with the first exemplary embodiment of thisdisclosure;

FIG. 15B depicts a schematic view of pinning two wafers via a center pinand an off-center anti-rotation pin, in accordance with the firstexemplary embodiment of this disclosure;

FIG. 15C depicts a schematic view of pinning two wafers via threeperipheral pins, in accordance with the first exemplary embodiment ofthis disclosure;

FIG. 16 is a schematic diagram of an exemplary wafer bonder, inaccordance with the first exemplary embodiment of this disclosure;

FIG. 17 is a schematic diagram of an exemplary bonder spacer flagmechanism used with a wafer bonder, in accordance with the firstexemplary embodiment of this disclosure;

FIGS. 18A-18B are schematic diagrams of one example of a pin, inaccordance with the first exemplary embodiment of this disclosure; and

FIG. 19 is a flowchart illustrating a method of placing aligned wafersinto a bonding device, in accordance with the first exemplary embodimentof the disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides an industrial-scale device for handlingprecisely aligned and centered semiconductor wafer pairs forwafer-to-wafer aligning and bonding applications with high throughput.The device includes an end effector that is attached at the end of arobotic arm. The end effector is configured to hold, move and place analigned pair of wafers into and out of various processing stationswithout changing the wafer-to-wafer alignment and without introducingany contaminants.

FIG. 1B depicts a schematic diagram of a transport device and methodused to transport aligned wafers 20, 30 from an aligner to a bondingdevice, in accordance with a first exemplary embodiment of thisdisclosure. As shown in FIG. 1B, an end effector 100 is attached to arobotic arm 80 and is configured to move into and out of an alignmentdevice 300 and a separate bonding station 400 having a bonding device. Apair of two wafers 20, 30 is carried by the end effector 100 into thealignment device 300 where the two wafers 20, 30 are aligned relative toeach other and their alignment is secured with the end effector 100.Next, the robotic arm 80 moves the end effector 100 with the alignedwafer pair 20, 30 out of the alignment device 300 and into the bondingstation 400, where the two aligned wafers 20, 30 can be bonded. The endeffector 100 is capable of placing the two aligned wafers 20, 30 in thebonding device and then the robotic arm 80 removes it from the bondingdevice for the duration of the bonding process. Once the bonding processis complete, the robotic arm 80 moves the end effector 100 back into thebonding device to collect the bonded wafer pair 20, 30, which aresupported by the end-effector 100 as it is removed from the bondingstation 400. In some embodiments, the alignment device 300 and thebonding station 400 are integrated into the same reactor.

FIG. 4 depicts an end-effector 100 used to transport aligned wafers intoand out of processing chambers, in accordance with a first exemplaryembodiment of this disclosure. The end effector 100 may include aY-shaped fixed frame 110 and a floating carrier 120 disposed on top ofthe frame 110. In one example, frame 110 has a semi-circular innerperimeter 110 a with a radius that approximately matches the radius ofthe wafers 20, 30. In other examples, frame 110 has a Y-shaped orfork-shaped inner perimeter. Similarly, carrier 120 has a semi-circularinner perimeter 120 a with a radius that approximately matches theradius of the wafers 20, 30. In accordance with this disclosure, thesemi-circular inner perimeter 120 a of the floating carrier 120 may beunderstood as a partial ring structure which has ends that terminatebefore a complete ring, e.g., 360°, is formed. As shown in FIG. 4, thestructure of the semi-circular inner perimeter 120 a may be formed froma floating carrier 120 with a partial ring shape that includessubstantially 180° of rotation, or in other designs the partial ringshape may be up to 270°. Other partial ring configurations of thefloating carrier 120 are also considered within the scope of the presentdisclosure.

The floating carrier 120 may be formed from a substantially planarstructure which is oriented in parallel to a plane of the frame 110 andpositioned spaced therefrom. The floating carrier 120 may include anumber of vacuum pads, such as three vacuum pads 122 a, 122 b, 122 c,that protrude inward towards a central axis 119 of the semi-circularinner perimeter 120 a. The three vacuum pads 122 a, 122 b, 122 c may bepositioned at three or more locations 111 a, 111 b, 111 c, of the innerperimeter 120 a, respectively. Vacuum pads 122 a, 122 b and 122 c may beused for holding the edges of a top wafer 20, as depicted in FIG. 5.

FIG. 5 depicts a top view of the end effector 100 of FIG. 4 holding apair of aligned wafers 20, 30, in accordance with the first exemplaryembodiment of this disclosure. FIG. 6 depicts a bottom view of the endeffector 100 of FIG. 4 holding a pair of aligned wafers 20, 30, inaccordance with the first exemplary embodiment of this disclosure.Referring to FIGS. 4-6, it is noted that the end effector 100 may beunderstood to have the floating carrier 120 positioned on a top sidethereof, while the frame member 110 is positioned on a bottom sidethereof. Unlike a conventional transport apparatus which carries both ofthe wafers of the aligned wafer pair on a top surface thereof, e.g., asdiscussed relative to FIGS. 2A-2C, the end effector 100 may carry thewafers 20, 30 interior of the arms of the frame member 110 and in aposition below the extended lip of the floating carrier 120. This designallows the edges of wafers 20, 30 to be held between the fixed frame 110and the floating carrier 120 in various locations about the innerperimeters 110 a, 120 a of the frame member 110 and the floating carrier120, such as in three locations 111 a, 111 b, 111 c via threeclamp/spacer assemblies 130 a, 130 b, and 130 c, respectively, as shownin FIG. 5 and FIG. 6. In particular, the top wafer 20, as shown in FIG.5, may be positioned against and retained by vacuum pads 122 a, 122 band 122 c on the underside of the floating carrier 120, while the bottomwafer 30 may be retained with mechanical clamps 132 a, 132 b, and 132 c.

FIG. 7 depicts a partially transparent bottom view of the end effectorof FIG. 4 holding a pair of aligned wafers, in accordance with the firstexemplary embodiment of this disclosure. FIG. 8A depicts across-sectional view of a portion of the end effector of FIG. 4 holdinga pair of aligned wafers, in accordance with the first exemplaryembodiment of this disclosure. With reference to FIGS. 4-8A, the endeffector 100 may further include a number of assemblies to hold and/orspace the wafers, such as assemblies 130 a, 130 b, and 130 c about theinner perimeter 110 a of the frame member 110. The assemblies 130 a, 130b, and 130 c may be located in a spaced position that substantiallymatches the spaced positioning of the vacuum pads 122 a, 122 b and 122c. Each of the assemblies 130 a, 130 b, and 130 c may include a carrierspacer flag 136 a, 136 b and 136 c, a mechanical clamp 132 a, 132 b, and132 c, and a limit-feature 134 a, 134 b and 134 c, respectively.

Limit-features 134 a, 134 b, 134 c may loosely couple and hold thefloating carrier 120 and the fixed frame 110 together. A gap 121 isformed between the floating carrier 120 and each of the limit features134 a, 134 b and 134 c, as shown in FIG. 8A. Gap 121 contributes tovibrational isolation of the floating carrier 120 from the fixed frame110, which may prevent vibrations originating in the robot carrying theend-effector 100 from being transmitted to the floating carrier 120 andalso allows the floating carrier 120 to seat in a compliant way on thetop wafer-to-chuck datum interface, as well as avoiding any harsh orstressful contact. The floating carrier 120 is configured to move up anddown along direction 90 of FIG. 8a , relative to the fixed frame 110,loosely guided by limit-features 134 a, 134 b, and 134 c. While thelimit-features 134 a, 134 b, 134 c may have varying designs, in oneexample, a lower portion of the limit-features 134 a, 134 b, 134 c maythreadedly connect to the frame member 110 while an upper portion ismovable relative to the floating carrier 120. For example, the upperportion of the limit-features 134 a, 134 b, and 134 c may include a headthat is locatable within a recessed cavity, e.g., recessed cavity 135 ain FIG. 8a , which allows for constrained movement of the floatingcarrier 120 relative to the frame member 110 in direction 90, therebyallowing control of a maximum size of the gap 121. Additionally, thesize of the limit-features 134 a, 134 b, and 134 c relative to therecessed cavity may be selected to provide small amounts of lateralclearance, such that the floating carrier 120 may be slightly adjustedlaterally relative to the frame member 110.

Carrier spacer flags 136 a, 136 b, 136 c are used to space the wafers20, 30 from one another when they are received by the end effector 100.In one example, the carrier spacer flags 136 a, 136 b, 136 b may beconstructed from stainless steel body with a titanium nitride coating,but various materials and coatings may also be used. Carrier spacerflags 136 a, 136 b, 136 c may be inserted underneath the edge of wafer20 in the corresponding three locations 111 a, 111 b, 111 c and thenwafer 30 is stacked underneath the spacer flags 136 a, 136 b, 136 c, asshown in FIG. 8A. The two stacked wafers 20, 30 may then be clampedtogether with clamps 132 a, 132 b, 132 c in the corresponding threelocations 111 a, 111 b, 111 c. Spacer flags 136 a, 136 b, 136 c areconfigured to move horizontally along direction 92 and clamps 132 a, 132b, 132 c are configured to move in a pivotal motion, along a linearslide, with a cam-type motion, or a combination thereof, to contact thebottom wafer 30. For instance, in one example, the clamps 132 a, 132 b,132 c may rotate about a pivot axis that is substantially parallel to anaxis of the semi-circular interior perimeter 120 a.

FIG. 7 also illustrates bonder spacer flags 138 a, 138 b, 138 c, whichare the spacer flags used by the bonding device to space the two stackedwafers 20, 30 when they are placed within the bonding device. As can beseen, the bonder spacer flags 138 a, 138 b, 138 c may be positioned inproximate locations to the end effector spacer flags 136 a, 136 b, 136c, which may be spaced substantially equidistantly about thesemi-circular perimeter of the floating carrier 120.

In some uses, it may be desirable to equip the end effector 100 with acentering and/or locking mechanism to center and/or lock the floatingcarrier 120 to the frame member 110. FIG. 8B depicts a cross-sectionalview of the end effector of FIG. 4 holding a pair of aligned wafers, inaccordance with the first exemplary embodiment of this disclosure.Specifically, FIG. 8B illustrates a centering mechanism 104 utilizing amoving tapered pin 105, which allows for re-centering of the floatingcarrier 120 to the frame member 110 in between each cycle of use. Pin105 is precision guided and driven by a motor or via pneumatic actuationon an axis at the fixed carrier 110. Pin 105 may be positioned within afirst hole 105 a in the frame member 110 and engages a precision fittedhole 105 b in the floating carrier 120. Pin 105 may be used for there-centering purpose or may also be used during transport to constrainthe floating carrier 120 to the frame member 110. In other designs, thepin 105 may be a fixed pin located on the frame member 110 which engagesa precision fitted hole 105 b in the floating carrier 120 when thedistance between the frame member 110 and the floating carrier 120 isvery small, i.e., smaller than the length of the pin 105 itself, and isreset when the floating carrier 120 moves back onto the frame member110.

FIG. 8B also illustrates the use of a mechanical clamp 106 which may beused to fix the frame member 110 to the floating carrier 120. Themechanical clamp 106 may be mounted to the fixed carrier 110 and maymove in a vertical direction or a rotational direction to engage theframe member 110 to the floating carrier to hold the floating carrier120 to the frame member 110 and to avoid position change of the floatingcarrier 120.

FIG. 8C depicts a cross-sectional view of the end effector of FIG. 4holding a pair of aligned wafers, in accordance with the first exemplaryembodiment of this disclosure. In FIG. 8C, an integrated fixedre-indexing pin and vacuum groove may be used to for clamping the framemember 110 to the floating carrier 120. As shown, the frame member 110may have a pin 106 extending into hole 105 b the floating carrier 120and a plurality of vacuum grooves 108 positioned on a surface of theframe member 110 that interfaces with the floating carrier 120. Anegative pressure may be applied to the vacuum grooves 108 to bias thefloating carrier 120 to the frame member 110 while the pin 106 acts tocenter the floating carrier 120 to the frame member 110.

FIG. 8D depicts a cross-sectional view of the end effector of FIG. 4positioned on a storage station, in accordance with the first exemplaryembodiment of this disclosure. As shown, the holes 105 a, 105 b withinthe frame member 110 and floating carrier 120 may be used during ahanding-off process with the end effector 100, such as to change betweendifferent end effectors 100. Specifically, the robotic arm on which theend effector 100 is carried, as is described relative to FIG. 10A, mayposition the end effector 100 near a storage station 86 which has a pin88 extending outwards. The end effector 100 may be guided over the pin88 of the storage station 86 until the pin 88 engages with the holes 105a, 105 b. Once the pin 88 is positioned within the holes 105 a, 105 b,the robotic arm may disconnect from the end effector 100, leaving theend effector 100 in a stowed away position on the storage station 86.The storage station 86 with the pin 88 may provide secure storage of theend effector 100 when it is not in use, as well as allow the robotic armto quickly change between different end effectors 100.

It is further noted that when the end effector 100 is removed from abonding device, the high temperature of the end effector 100 may bemonitored using an integrated thermocouple positioned on the framemember 110, or on another part of the end effector 100. In anotherdesign, the storage station 86 may be equipped with a thermocouple toallow for thermal monitoring of the end effector 100 when it is stowedin the storage station 86. Further, when the end effector 100 is placedin the storage station 86, it may desirable for it to be cooled to alower temperature, either through natural cooling or with a coolingdevice.

FIG. 9 depicts a bottom view of the end effector 100 with vacuum pads122 a, 122 b and 122 c that are adjustable to hold wafers of differentsizes, in accordance with the first exemplary embodiment of thisdisclosure. As shown, the vacuum pads 122 a, 122 b and 122 c may bemovably connected to the floating carrier 120 such that they can beradially adjusted along the semi-circular interior perimeter 120 a,e.g., along directions 123 a, 123 b such that they can be moved closerand further towards a center point of the semi-circular interiorperimeter 120 a. FIG. 9 illustrates broken boxes showing the generaloutline of the vacuum pads 122 a, 122 b and 122 c in two exemplarypositions: one where they are positioned closer towards the center pointto hold a smaller wafer size 22 b and one where they are positionedfurther from the center point to hold a larger wafer size 22 a. Thevacuum pads 122 a, 122 b and 122 c may be adjustable to various degreesto accommodate a plurality of differently sized wafers.

FIGS. 10A-10B depict the end effector 100 in use with a robotic arm 80,in accordance with the first exemplary embodiment of this disclosure. Asshown, the end effector 100 may be removably attached to the robotic arm80 (shown schematically in FIG. 10A) and may be interchanged with adifferent size or different shaped end effector depending upon the sizeand number of wafers that need to be supported. The robotic arm 80 maybe positioned proximate to an alignment device 300 to allow for removalof the wafers 20, 30 carried on the end effector 100 from the alignmentdevice 300. The robotic arm 80 may also be located near the bondingdevice (not shown), so the wafers 20, 30 can be transported between theprocessing units using a tool exchanger 84 at the end of the robotic arm80. In one example, the tool exchanger 84 may be a Schunk Type SWS-011,but other tool exchanges may be used as well. In comparison toconventional transport fixtures, the end effector 100 has a reducedweight which significantly reduces robot loading. The end effector 100also doesn't need to flip the pairs of aligned wafers 20, 30 about theaxis of the interchange 82 of robot 80, e.g., to switch relativevertical positions of the top and bottom wafers 20, 30, respectively,which results in easier handling overall and a lower alignment shiftrisk.

Using the end effector 100 described relative to FIGS. 4-10B, a waferpair 20, 30 may be placed in an aligner within an alignment device 300and aligned in accordance with the methods and processes known in theart. Once aligned, the end effector 100 may be used to remove thealigned wafer pair 20, 30 from the aligner. FIGS. 11A-11H schematicallydepict cross-sectional illustrations of the steps of unloading analigned wafer pair 20, 30 from an aligner with the end effector 100 ofFIG. 4, in accordance with the first exemplary embodiment of thisdisclosure. While each of the figures generally illustrates only asingle assembly 130 a of the end effector 100, it is noted that the samefunctions may also be completed by the other assemblies included withthe end effector 100, such that the same or similar functions areoccurring at three or more points on the end effector at the same timeor at differing but predetermined times.

First, FIG. 11A depicts the wafers 20 and 30 which have been alignedrelative to each other and are held in contact with an upper wafer chuck320 and a lower wafer chuck 330 of an alignment device 300. In thealignment device 300, the upper stage carrying the upper wafer chuck 320is fixed while the lower stage carrying the lower wafer chuck 330 ismovable vertically, i.e., in the z direction, as indicated at 98. Thewafers 20, 30 have been aligned in the x direction, e.g., direction 92in FIG. 11B, the y direction (out of the page), and angularly relativeto one another such that the wafers are parallel. Wafers 20, 30 haveedges 20 e, 30 e, respectively, and edges 20 e, 30 e protrude from thesides of chucks 320 and 330 of the alignment device 300.

As shown in FIG. 11B, the end effector 100 is brought close to the sidesof chuck 320 and 330 of the alignment device 300 along direction 91 tobegin the unloading process. Shown schematically, the end effector 100has the frame member 110 which may be fitted to a robot (not shown),while the floating carrier 120 is movable relative to the frame member110 along direction 90. For simplicity in description, the frame member110 may be considered to be fixed, in that, it is stationary relative tothe end portion of the robot to which the end effector 100 is attached,while the floating carrier 120 is considered to be movable, in that, itis movable relative to the end portion of the robot to which the endeffector 100 is attached. The limit-feature 134 a is connected to theframe member 110 and positioned within the hole 135 a in the floatingcarrier 120, where the clearance spaced between the limit-feature 134 aand the sidewall of the hole 135 a allow slight lateral movements of thefloating carrier 120 relative to the frame member 110 along direction92.

In this starting state shown in FIG. 11B, the end effector 100 ispositioned proximate to the alignment device 300 in an openconfiguration, with the various clamps and spacing devices retracted.The floating carrier 120 is in a coupled or contacted position with thefixed carrier 110. Next, as shown in FIG. 11C, the floating carrier 120is decoupled from the frame member 110 while the end effector 100 movesdown along direction 97 b, the z direction. Decoupling of the floatingcarrier 120 from the frame member 110 may be critical in preventingsmall vibrations in the robot carrying the end effector 100 from beingtransferred to the alignment device 300 and causing unintended movementsof the wafers 20, 30 and causing them to become misaligned. The movementof the end effector 100 may be only a few millimeters until vacuum pads122 a are in contact with the top surface of edge 20 e of wafer 20 andthe distance between the fixed frame 110 and the floating carrier 120increases so that the carrier spacer flags 136 a, 136 b, 136 c are belowthe bottom surface of edge 20 e of wafer 20. In this position,optionally, the vacuum pads 122 a may be activated to effectivelyconnect or lock the floating carrier 120 to the top wafer 20.

Next, in FIG. 11D, the spacer flag 136 a moves horizontally alongdirection 92 a, the x direction, so that it is positioned between thebottom surface of edge 20 e of wafer 20 and the top surface of edge 30 eof wafer 30. Spacer flags 136 a, 136 b, 136 c, are flexible in thez-direction so that they can comply with the surfaces of the wafers 20 eand 30 e, without applying any significant force onto the surfaces.Next, as shown in FIG. 11E, the lower wafer chuck 330 is moved up alongdirection 96 a until the top surface of edge 30 e of wafer 30 touchesthe bottom surface of spacer flag 136 a, which forms the gap between thewafers 20, 30. Next, clamp 132 a is moved to contact the bottom surfaceof edge 30 e of wafer 30 and to clamp the edges 20 e, 30 e of wafers 20,30, respectively together with the inserted spacer flag 136 a in betweenthem, as shown in FIG. 11F. In this position, the wafers 20, 30 arelocked together with the spacer flag 136 a therebetween, all of whichare held by the end effector 100. To release the wafer pair 20, 30 fromthe alignment device 300, the upper wafer chuck 320 may be purged andthen the lower wafer chuck 330 is moved down along the z axis indirection 96 b to a mid-position, thereby creating a spaced distancebetween the top wafer 20 and the upper wafer chuck 320. Then the vacuumof the lower wafer chuck 330 is released and it is moved further downthe z direction until the aligned wafer pair 20, 30 is held entirely bythe end effector 100 at the edges 20 e, 30 e, and is ready to betransported out of the alignment device 300, as shown in FIG. 11H.

FIG. 12 is a schematic diagram of a wafer alignment device 300, inaccordance with the first exemplary embodiment of this disclosure. Thewafer alignment device 300 may serve as an example of the aligner inwhich the process of FIGS. 11A-11H is used. As shown in FIG. 12, thealignment device 300 may further include a spacer flag carriage 360 withpneumatic Z-axis, a static support bridge 365, a support frame 390, thetop substrate chuck 320, the bottom substrate chuck 330 and the WECspacer flag mechanisms 380, which are also described in U.S. Pat. No.8,139,219 entitled “APPARATUS AND METHOD FOR SEMICONDUCTOR WAFERALIGNMENT”, which is commonly owned and the contents of which areexpressly incorporated herein by reference.

FIGS. 13A-13H schematically depict cross-sectional illustrations of thesteps of loading an aligned wafer pair into a bonder with the endeffector of FIG. 4, in accordance with the first exemplary embodiment ofthis disclosure. One of the processing stations where the aligned wafers20, 30 can be transported and loaded with the robotic arm 80 and the endeffector 100 is a bonder 400. FIG. 13A illustrates the bonder 400 in anidle state, prior to the wafers being placed within the bonder chamber410. The bonder 400 includes a bottom chuck 430 and a top chuck 420positioned below and above the bonder chamber 410, both of which arecapable of maintaining a heated state to bond the wafers. One or both ofthe top and bottom chucks 420, 430 may be movable vertically along the zaxis. In many bonder 400 designs, only one of the chucks will be movablewhile the other will remain stationary. Bonder spacers 138 a areincluded in the bonder 400 and may be attached to the lower stage of thebonder 400, such that the bonder spacer flag 138 a moves vertically withthe bottom chuck 430, thereby maintaining a constant relative positionto the bottom chuck 430. While each of the figures generally illustratesonly a single bonder spacer flag 138 a for clarity in disclosure, it isnoted that three or more bonder spacer flags 138 a, 138 b, 183 c (FIG.7) may be used in the bonder 400 such that the same or similar functionsare occurring at three or more points in the bonder at the same time orat differing but predetermined times.

The bonding process using the end effector 100 differs substantiallyfrom the bonding process using conventional transport fixtures.Conventional transport fixtures transport aligned wafers into a bondingdevice and must remain in the bonding device throughout the duration ofthe bonding process. In contrast, the end effector 100 of the subjectdisclosure allows for the transportation of aligned wafers into abonding device and then is removed from the bonding chamber prior to thebonding process. Accordingly, the end effector 100 may be subjected toonly brief durations of idle temperatures in the bonding devices, e.g.,approximately 300° C., as compared to the 500° C. temperatures andhour-long durations that conventional transport fixtures are subjectedto. As a result, the end effector 100 experiences less mechanical andthermal stress and requires less maintenance, which acts to increaseefficiency and reduce costs.

As an overview, bonding in accordance with this disclosure is achieved,in part, due to the use of bonder spacer flags 138 a which are insertedbetween the wafers thereby allowing the end effector spacer flags 136 a,136 b, and 136 c to be removed, and the entire end effector 100 to beremoved from the bonding chamber. The aligned and spaced wafers are thenpinned with pins 455 a, 455 b and 455 c and then a bonding force isapplied on the pinned wafers 20, 30. Once bonding is complete, the endeffector 100 may be used to remove the bonded wafers from the bondingdevice.

Additional details of the process for loading the aligned pair of wafers20, 30 in the bonder 400 with the end effector 100 are provided relativeto FIGS. 13B-13H. Referring first to FIG. 13B, aligned and clampedwafers 20 and 30 are carried by the end effector 100 and inserted intothe bonder chamber 410. In this bonder configuration, top chuck 420 isfixed and bottom chuck 430 is movable along direction 425 via z-drive450, but it is noted that the bonder 400 may have any configuration ofmovable and fixed chucks. As previously mentioned, the end effectorholds the edges 20 e, 30 e, of wafers 20, 30 with clamping assemblies130 a, 130 b, and 130 c, and wafers 20, 30 are inserted into the bonderchamber 410 along direction 99, so that edges 20 e, 30 e protrude fromthe loading side of the bonder 400, as shown in FIG. 13B. In thisstarting state, the floating carrier 120 is in contact with the framemember 110 and wafer edges 20 e, 30 e are clamped together.

Next, as shown in FIG. 13C, the floating carrier 120 with the clampedwafers 20, 30 decouples from the frame member 110 such that it movesdown along direction 90 b and wafers 20, 30 are placed on the bottomchuck 430, so that the bottom surface of wafer 30 is in contact with thetop surface of the bottom chuck 430. In one of many alternatives, thefloating carrier 120 with the clamped wafers 20, 30 could move up alongdirection 90 a and wafers 20, 30 are placed on the bottom surface of thetop chuck 420, so that the top surface of wafer 20 is in contact withthe bottom surface of the top chuck 420. As shown, the bottom chuck 430may have one or more cutouts 432 along portions of the perimeter of thebottom chuck 430, which may allow for adequate clearance for the endeffector 100 to place the wafers 20, 30 within the bonder 400, e.g., sothe outer edges of the wafers 20, 30 can be substantially aligned withthe perimeter of the top and bottom chucks 420, 430. Next, while the endeffector spacer flag 136 a remains in a position between the wafers 20,30, one or more pins 455 a are brought into contact with the top surfaceof wafer 20 in one or more locations, as shown in FIG. 13D.

Within the industry, it is desirable to bond wafers as efficiently aspossible to increase production. One technique for increasing theproduction of bonded wafer pairs is to maintain a high temperature inthe bonder 400 even when it is not actively bonding wafers, therebydecreasing the time required for the bonder 400 to get up to anoperating temperature at each cycle. However, placing aligned waferswithin an already heated bonder 400, e.g., on the order of 400° C., canaffect the alignment of the wafers 20, 30. For example, subjecting thewafers 20, 30 to this type of heated environment can result in thewafers 20, 30 expanding radially, so it is desirable to pin the wafers20, 30 together quickly and as accurately as possible. While the wafers20, 30 can be pinned at different locations, it may be preferable to pinthe wafers 20, 30 together at a center point thereof instead of along aradial edge, thereby preventing situations where thermal expansions ofthe wafers 20, 30 from an offset point causes misalignments. In FIGS.13D-13F, pin 455 a is shown located at a center of the wafers 20, 30,but the number of pins 455 a and the locations of those pins can vary,as discussed relative to FIGS. 15A-15C.

Then, as shown in FIG. 13E, while the wafers 20, 30 are retained withthe one or more pins 455 a, one or more of the bonder spacer flags 138a, positioned proximate to edge portions of the wafers 20, 30, areinserted between wafers 20, 30 along direction 411 b. The bonder spacerflags 138 a may be thinner than the end effector spacer flag 136 a, andtherefore they can be inserted between the wafers 20, 30 clamped aroundthe end effector spacer flag 136 a. In one example, the bonder spacerflags 138 a may be approximately 100 microns whereas the end effectorspacer flag 136 a may be approximately 200 microns.

Next, clamps 132 a, 132 b, 132 c are released and they disengage fromthe edge 30 e of the bottom surface of wafer 30, as shown in FIG. 13F.It is noted that the clamps may be removed in accordance withpredetermined routines, such as in unison, sequentially, or acombination thereof. After release of the clamps 132 a, 132 b, and 132c, the end effector spacer flag 136 a is removed from the space betweenthe two wafers 20, 30 along directions 92 b, as shown in FIG. 13G. Thethree or more bonding spacer flags 138 a remain in a position betweenthe wafers 20, 30 about the perimeter of the wafers 20, 30. Commonly,the bonder spacer flags 138 a will be positioned close to the locationsof the end effector spacer flag 136 a along the perimeter of the wafers20, 30, as shown in FIG. 9. After the end effector spacer flags 136 aare removed, a spaced gap between the wafers 20, 30 may still bepresent, as shown in FIGS. 13G-13H, due to the nearby bonder spacer flagremaining between the wafers 20, 30.

Finally, the end effector 100 moves up along direction 97 a until thevacuum pads 122 a, 122 b, 122 c, disengage from the top surface of edge20 e of wafer 20, leaving behind the pinned wafers 20, 30 on top of thebottom chuck 430, as shown in FIG. 13H. At this stage, the end effector100 is removed from the bonder 400 entirely, as shown in FIG. 13I, andthe wafer bonding can begin. In the initial stages of the wafer bondingprocess, wafers 20, 30 are bonded together about the bonder spacer flags138 a. Prior to the force application, the bonder spacer flags 138 a arebe removed. After completion of the bonding process, the bonded waferpair 20, 30 is removed from the bonder 400 with the end effector 100.

FIG. 14 depicts a bonder positioned to receive the end effector of FIG.4, in accordance with the first exemplary embodiment of this disclosure.Specifically, the bonder 400 of FIG. 14 may have differently designedfixed and movable components. In FIGS. 13A-13H, the bonder 400 isdesigned so that the upper chuck 420 is fixed and the lower chuck 430 ismovable along the z axis. In the design of the bonder 400 shown in FIG.14, the lower chuck 430 is fixed and the upper chuck 420 moves alongdirection 426, until the bottom surface of the upper chuck 420 contactsthe top surface of the top wafer. All variations on movement of the topand/or bottom chucks 420, 430 of a bonder 400 may be used with thedevices, system, and methods of this disclosure.

FIGS. 15A-15C illustrate variations in the pins used in a bonder. FIG.15A depicts a schematic view of pinning two wafers via a single centerpin, in accordance with the first exemplary embodiment of thisdisclosure. FIG. 15B depicts a schematic view of pinning two wafers viaa center pin and an off-center anti-rotation pin, in accordance with thefirst exemplary embodiment of this disclosure. FIG. 15C depicts aschematic view of pinning two wafers via three peripheral pins, inaccordance with the first exemplary embodiment of this disclosure. Withreference to FIGS. 15A-15C together, one or more of the pins 455 a, 455b, 455 c may be brought into contact with the top surface of wafer 20 inone or more different locations. It may be preferable to use a singlepin 455 a positioned in the center of the wafers 20, 30, as shown inFIG. 15A. Using a single pin 455 a in the center may allow the wafers20, 30 to thermally expand without experiencing misalignments.

In one alternative, the wafers 20, 30 may be pinned with two pins 455 a,455 b, as shown in FIG. 15B. Here, pin 455 a is a center pin and pin 455b is an anti-rotation pin, such that pin 455 b prevents a rotation ofthe wafers 20, 30. In this design, the center pin 455 a may apply agreater pinning force to the wafers 20, 30 than the anti-rotation pin455 b. Additionally, the off centered pin 455 b may be radiallycompliant, in that it may be movable along a radius of the wafers 20, 30to accommodate for thermal expansion of the wafers. In anotheralternative shown in FIG. 15C, three pins 455 a, 455 b, 455 c may beused, where they are arranged at the periphery of wafers 20, 30, such asnear each of the bonder spacer flags 138 a. They may be spacedsubstantially equidistantly about the wafer 20, 30 perimeter, such as at120 degrees apart from each other. It is also possible to use acombination of these configurations or other pin configurations notexplicitly shown. For example, it may be desirable to use the center pinof FIG. 15A with the three perimeter pins of FIG. 15C.

FIG. 16 is a schematic diagram of an exemplary wafer bonder, inaccordance with the first exemplary embodiment of this disclosure. Asshown in FIG. 16, the bonder 400 further includes a pressure head 460with membrane force and motor positioning, a bond head 470 with pressureplate and upper pins 455, bonder spacer flag mechanism 480, lower heater490 with sandwich plate and purge features and a static Z-axis supportcolumn 495. These and other components of the bonder 400 are describedin U.S. Pat. No. 7,948,034 entitled “APPARATUS AND METHOD FORSEMICONDUCTOR BONDING”, which is commonly owned and the contents ofwhich are expressly incorporated herein by reference.

FIG. 17 is a schematic diagram of an exemplary bonder spacer flagmechanism 480 used with a wafer bonder 400, in accordance with the firstexemplary embodiment of this disclosure. With reference to FIGS. 16-17,the bonder spacer flag mechanism 480 may be used to move the bonderspacer flags 138 a, 138 b, 138 c (shown in FIG. 7) between inserted andretracted positions between aligned wafer pairs. In one example, thebonder spacer flag mechanism 480 may have a pneumatic piston 482 mountedto a ring 484 positioned around the Z-axis column 495 and below thelower heater 490. The pneumatic piston 482 carries a shelf 486 thatsupports the bonder spacer flag 138 a. When the pneumatic piston 482 isactivated, it is movable towards and away from the center of the bondingfield in a radial direction. The movement of the bonder spacer flag 138a may be guided by a rail 488 which the shelf 486 is slidable on. Thesestructures may allow the bonder spacer flags 138 a to have radialcompliance, thereby allowing the bonder spacer flags 138 a to move in aradial direction with the wafers 20, 30 as the wafers experience thermalexpansion. Other mechanical and electromechanical devices beyondpneumatically-controlled devices may also be used to move the bonderspacer flag 138 a.

Conventional bonding devices have used one or more pins to compresswafers, but these devices offer limited force control over the pin. Inone example, a conventional pin had a single force that was created by acompression spring or similar device that could only apply constantpressure to the wafers. As a result, when the top and bottom chuckscompressed the wafers, the area of the wafers that aligned with the pinhad less pressure applied to it than the areas of the wafer contacted bythe chucks, which caused a mechanical high yield loss at the portion ofthe wafer in contact with the pin. At the same time, the lower thermalconductivity of the conventional pin caused a thermal high yield loss atthe portion of the wafer aligned with the pin. When these problems arecombined with the fact that conventional pins have larger diameters anda large surround gap, commonly around 12 mm-14 mm, mechanical andthermal high yield loss adds up to be a significant inefficiency inwafer bonding.

To overcome these problems, the subject disclosure contemplates a pin455 a that decreases both the mechanical yield loss and the thermalyield loss. To this end, FIGS. 18A-18B are schematic diagrams of oneexample of a pin 455 a, in accordance with the first exemplaryembodiment of this disclosure. As shown, the pin 455 a may extendthrough the top chuck 420 of the bonding device such that it can bemovable into the bonder chamber 410 area where the wafers (not shown)would be positioned for bonding. In one example, the pin 455 a may be 5mm in diameter and positioned within a 6 mm bore within the top chuck420 to give the pin 455 a approximately 0.50 mm of clearance to the topchuck 420. In comparison to prior art pins having a pin and gap diameterof roughly 12 mm-14 mm, the pin 455 a having a 6 mm diameter with gapmay greatly improve the mechanical high yield loss. Additionally, unlikeconventional pins which use a compression spring to provide themechanical force, the pin 455 a may use a pneumatic actuator to controlthe force of the pin 455 a on the wafers. As a result, the pressureexerted by the pin 455 a may be selected to substantially match thepressure force of the chucks, thereby further decreasing the mechanicalyield loss.

The pin 455 a may be constructed from titanium, ceramics such as siliconnitride ceramics, or other materials, and may include a center pin 502which is surrounded by a lower tube or sleeve 504 positioned along abottom portion of the pin 455 a, and an upper tube or sleeve 505 havinga thin wall and positioned along an upper portion of the pin 455 a. Thelower sleeve 504 and the upper sleeve 505 may be connected together at ajoint proximate to the center pin 502, such as with welding or anothertechnique. The center pin 502 may include a pin tip 506 that is flat.The upper sleeve 505 may be actively heated by the surrounding chuck 420and/or a heater pin 532 in abutment with a heater 526 positioned abovethe chuck 420, as is further described relative to FIG. 18B, and thecenter pin 502 may also be heated by the surrounding chuck 420.Additionally, it is possible to heat components of the pin 455 a with aresistive heating element interfaced with the structures of the pin 455a. In some designs, both passive heating from the chuck 420 and activeheating from a resistive element heating may be used to heat the variouscomponents of the pin 455 a.

The pin 455 a may be radially compliant near the tip, such that it ispreloaded to center at +/−0.5 mm with top center locating to allow thepin tip 506. Preloading the pin 455 a allows the pin 455 a to have anatural, centered position when actuated but also allows the pin 455 ato be radially compliant once under force. As a result, the pin 455 acan maintain an application of normal force on the wafers.

Additional mechanics of the pin 455 a are shown in detail in FIG. 18B.The pin 455 a is positioned substantially centered within a centerhousing 510 having a center pin bushing 512, also known as a peekbushing, which itself has a bushing fit with a short length-to-diameterratio 514, which is used for locating the pin 455 a. The center pinbushing 512 provides electrical isolation of the pin 455 a from thesurrounding mechanics of the bonder 400, which is important for anodicbonding processes where significantly high voltages may be used to bondthe wafers. The chamber lid 516 and a steel force reaction plate 518 arealso positioned surrounding the center pin bushing 512. Towards a lowerend of the center pin bushing 512 is a low force pre-load to centerradial compliant O-ring 520, which may be manufactured from silicone orsimilar materials. The O-ring 520 allows the center pin 502 andsurrounding tube 504 to move radially within the bonder 400. An aluminumcooling flange 522 is positioned below the force reaction plate 518, anda thermal isolation member 524 is positioned below the cooling flange522 to thermally isolate the heater 526.

Internal of the cooling flange 522 is a bushing 528 which surrounds aportion of the center pin 502. The bushing 528 and the thermal isolationmember 524 may be constructed from lithium aluminosilicateglass-ceramic, such as one sold under the tradename ZERODUR®, or asimilar material. The bushing 528 may have inset cavities 530 on eitherside which act as overlap features to provide electrical isolation withlow air dielectric in a vacuum. Positioned below the bushing 528 andaround the lower edge of the center pin 502 and tube 504 is a heater pin532. The heater pin 532 may be formed from silicon nitride and may beengaged with the lower inset cavity 530 of the bushing 528. The heaterpin 532 may also interface the center pin 502 and tube 504 along thethickness of the heater 526 and at least a portion of the upper chuck420. The positioning of the heater pin 532 in abutment with the heater526, as well as the material used to construct the heater pin 532, mayallow for efficient thermal transfers from the heater 526 through theheater pin 532 and to the center pin 502 and tube 504. This can allowthe center pin 502 and tube 504 to have a temperature that substantiallymatches the temperature of the top chuck 420, since all structures arepositioned to adequately transfer the heat from the heater 526 to theportions of the wafers they contact. Accordingly, the thermal yield lossthat conventional pins experience may be improved significantly.Increasing the thermal connectivity of the pin 455 a while being able tocontrol a force of application of the pin 455 a can improve the bondingof the wafers over that previously attained by the prior art.

FIG. 19 is a flowchart 600 illustrating a method of placing alignedwafers into a bonding device, in accordance with the first exemplaryembodiment of the disclosure. It should be noted that any processdescriptions or blocks in flow charts should be understood asrepresenting modules, segments, portions of code, or steps that includeone or more instructions for implementing specific logical functions inthe process, and alternate implementations are included within the scopeof the present disclosure in which functions may be executed out oforder from that shown or discussed, including substantially concurrentlyor in reverse order, depending on the functionality involved, as wouldbe understood by those reasonably skilled in the art of the presentdisclosure.

As is shown by block 602, wafers are secured in spaced alignment with anend effector having a frame member and a floating carrier movablyconnected to the frame member. A robot is used to move the end effector,thereby moving the wafers into a bonding chamber of a bonder (block604). The wafers are unloaded from the end effector (block 606). The endeffector is removed from the bonding chamber (block 608). The wafers arebonded (block 610). The method may further include any of the steps,processes, or functions disclosed relative to any figure of thisdisclosure.

It should be emphasized that the above-described embodiments of thepresent disclosure, particularly, any “preferred” embodiments, aremerely possible examples of implementations, merely set forth for aclear understanding of the principles of the disclosure. Many variationsand modifications may be made to the above-described embodiment(s) ofthe disclosure without departing substantially from the spirit andprinciples of the disclosure. All such modifications and variations areintended to be included herein within the scope of this disclosure andthe present disclosure and protected by the following claims.

What is claimed is:
 1. An end effector apparatus for handling waferscomprising: a frame member having a Y-shaped frame; a floating carrierconnected to a front end of the frame member with a gap formedtherebetween, wherein the floating carrier has a semi-circular interiorperimeter proximate to the front end of the frame member and the framemember including two arms at the front end of the frame member; and aplurality of vacuum pads connected along the semi-circular interiorperimeter of the floating carrier, wherein each of the plurality ofvacuum pads extend inward of the semicircular interior perimeter of thefloating carrier.
 2. The end effector apparatus of claim 1, wherein theplurality of vacuum pads are movably connected to the floating carrierand radially adjustable along the semi-circular interior perimeter. 3.The end effector apparatus of claim 1, wherein the floating carrier ismovably connected to the frame member and adjustable along an axis ofthe semi-circular interior perimeter, wherein a size of the gap isadjustable.
 4. The end effector apparatus of claim 3, wherein aplurality of limit features loosely couple the floating carrier to theframe member.
 5. The end effector apparatus of claim 1, furthercomprising a plurality of clamp-spacer assemblies connected to at leastone of the frame member and the floating carrier, each of theclamp-spacer assemblies having at least one spacer flag and at least onemechanical clamp.
 6. The end effector apparatus of claim 5, wherein theplurality of clamp-spacer assemblies are spaced substantiallyequidistantly on the semi-circular interior perimeter of the floatingcarrier.
 7. The end effector apparatus of claim 5, wherein the at leastone mechanical clamp is positioned below a bottom surface of thefloating carrier.
 8. The end effector apparatus of claim 1, furthercomprising a centering mechanism removably engagable with the framemember and the floating carrier, wherein the centering mechanismprevents a position change of the floating carrier relative to the framemember.
 9. The end effector apparatus of claim 8, wherein the centeringmechanism further comprises a pin removably engagable between a firsthole within the frame member and a second hole within the floatingcarrier, wherein engagement of the pin in the first and second holesaligns the floating carrier to the frame member along a direction of anaxis of the semi-circular interior perimeter of the floating carrier.10. The end effector apparatus of claim 8, wherein the centeringmechanism further comprises a mechanical clamp.
 11. The end effectorapparatus of claim 8, wherein the centering mechanism further comprisesa vacuum clamp.
 12. A laser pre-bond device comprising the end effectorof the claim 1 for a laser pre-bond process.
 13. An end effectorapparatus for handling wafers comprising: a frame member with asemi-circular inner perimeter at its front end; a floating carrierconnected directly to the front end of the frame member with a gapformed therebetween, wherein the floating carrier has a semi-circularinterior perimeter; and a plurality of vacuum pads connected along thesemi-circular interior perimeter of the floating carrier, wherein eachof the plurality of vacuum pads extend inward of the semi-circularinterior perimeter of the floating carrier.
 14. The end effectorapparatus of claim 13, wherein the semicircular interior perimeter ofthe floating carrier is similar to the semi-circular inner perimeter ofthe frame member.